This invention relates to an auxiliary device for use with a metered-dose aerosol container, either with or without an actuator. The aerosol container, with or without actuator, is referred to below as a metered-dose aerosol device. In particular, the invention relates to a spacer device to be attached to a metered-dose aerosol device for use in infants and young children to enable them to inhale medicaments such as, for example, bronchodilators and corticosteroids.
There are a substantial number of infants and young children generally termed "wheezy infants" who suffer from wheezy bronchitis, and other bronchopulmonary diseases such as respiratory distress syndrome due to post hyaline membrane disease and broncho-pulmonary dysplasia or neonatal pneumonia. These diseases if left untreated will in a significant number of cases develop into asthma. These conditions and other conditions such as cystic fibrosis will respond to treatment with for example, inhaled bronchodilators and corticosteroids provided there is a suitable device able to administer the medicaments so that they can reach the lungs of the infants and young children.
Administration of medicaments to infants and young children by inhalation is currently carried out using electric nebulisers but these devices have the disadvantage that they cannot be used with infants at home or the medicaments have to be administered over a time consuming period for example up to 10 minutes making it difficult to obtain the cooperation of the infant. It can be appreciated that if treatment is to continue for example, 3 or 4 times a day, this can be inconvenient. There is also considerable loss of medicament with this method of administration.
Existing large volume spacers, typically having a volume of about 750 ml, which are on the market when used for infants and young children have the disadvantage that the volume is too large for the infants' lungs and the inlet valve has too high a resistance and does not work in a vertical position for use in infants.
It has been proposed to provide a spacer device for use by infants and young children. However, only one such device is commercially available anywhere. This device uses a chamber having a volume of about 140 ml which is adapted at one end to receive the outlet of a metered-dose inhaler. The chamber is 110 mm long, and at its other end it communicates via an inhalation valve, which is in the form of a slit membrane, with a mask intended to be placed over the nose and mouth of an infant or young child.
This device, however, has several disadvantages, the appreciation of which forms part of the present invention. Thus, it has been found that the inlet valve does not open sufficiently to enable the infants to inhale sufficient medicament. Also, a disadvantage has been appreciated in that because there is no separate exhalation valve the exhaled air can only be released by leakage around the edge of the mask.